So much for the previous notions that panda porn and Viagra would encourage pandas to reproduce.

As one of the world’s most endangered species, there are less than 1,600 pandas living today, 300 of which live in zoos. In efforts to prevent extinction, researchers have been trying to get pandas to mate for decades. Despite creative ideas like drugs and watching other pandas mate, these efforts generally flop, desperately resulting in artificial insemination. Until now.

Panda experts in China’s Sichuan Province announced Thursday that they may have cracked the code behind panda reproduction. The secrets: strong hind legs and better hearing.

What makes these two characteristics so necessary? Better hearing enables pandas to hear the short period of time their mate is heating (ready to mate) each year. Leg strength helps in during reproduction, in more apparent ways.

Pandas have a very low rate of natural reproduction, due to their short annual estrous period. Translation: there’s only a two week slot each year when pandas can reproduce.